The present invention relates to pipe branch fittings intended for use where a pipe branch or branch appliance is to be attached over a hole pre-cut in the wall of a main pipe. The branch may be in the form of a pipe section, or as is common in building sprinkler systems, may be a water sprinkler head, or other branch appliance. The present invention is an improved version of the pipe branch fitting described and claimed in my U.S. Pat. No. 4,073,513, issued Feb. 14, 1978, which earlier patent is hereby incorporated by reference. The improvement disclosed herein resides essentially in the elimination of the need for a separate "fitting part", as that term is used in my earlier patent. In place of the fitting part, the present invention utilizes a modified branch appliance. This improvement significantly simplifies both the manufacturing and installation of the pipe branch fitting and the branch appliance. Moreover, the use of my improved pipe branch fitting significantly reduces the installation time required with prior art branch fittings, which require the installer to "dope" or TEFLON (polytetrafluorothylene) tape the threaded portion of the sprinkler head or other branch appliance received in the branch fitting. In the branch fitting of the present invention a resilient sealing gasket accomplishes this sealing function, thus eliminating this time-consuming and tedious installation step. Furthermore, the elimination of an additional threaded connection (i.e. the additional connection of the fitting part) at the location of each pipe branch fitting increases the reliability of the entire liquid distribution system with which my improved branch fitting is used, as it eliminates numerous potential sources of leakage in the system.
Another advantage of my improved pipe branch fitting over the prior art resides in the tapered profiling of the end walls of the body portion of the fitting. As seen in my U.S. Pat. No. 4,073,513, the end walls of the body of the fitting are oriented generally perpendicularly to the longitudinal axis of the pipe with which they are used. In contrast, the end walls of my improved pipe branch fitting are preferably slanted axially inwardly towards one another to produce a branch fitting of tapered side profile. This slanting of the end walls assists installers of the piping system by allowing easier movement of pipe lengths, on which a plurality of the pipe branch fitting have already been positioned, across building on ceiling cross-members. The disadvantage with previous pipe branch fittings not having this feature is that the perpendicular end walls of the branch fitting body act as "stops" when in contact with such cross-members, requiring added effort on the part of the installers to lift the entire pipe length and attached branch fittings at each crossing. The tapered design of my improved branch fitting allows the body of the fitting to " ride" over the cross-members, since the slanting of each end wall acts as a cam to assist in overriding these objects when normal push-through action combined with rotation of the pipe length is used. Additionally, the tapered branch fitting body results in an approximate 20% reduction in material weight, which also assists installation and reduces production costs.
There is also disclosed, according to the present invention, a novel shipping plug, of plastic or similar material, which may be placed in a threaded boss of the pipe branch fitting so as to allow pre-positioning of the pipe branch fittings and enclosed sealing gaskets over the pre-cut holes in the wall of the main pipe, prior to job-site shipping or installation.
There is thus provided, according to one aspect of the present invention, in combination, an improved pipe branch fitting and branch appliance for use with a pipe having a pre-cut hole. The branch fitting comprises an embracement member having a cylindrical inner surface adapted for embracement around the pipe at the position of the hole. An upstanding, hollow, internally threaded boss is positioned on one side of the embracement member, and a resilient sealing gasket is located on the inner side of the boss. The branch appliance, which is, preferably, a sprinkler head assembly, comprises a threaded portion adapted for retention in the threaded boss of the embracement member, and a generally planar annular surface bearing on the sealing gasket. The threaded portion is formed adjacent its inner end with a reduced diameter spigot end portion. The spigot end portion is sized and otherwise adapted for positioning in the pre-cut hole of the pipe. The branch appliance is provided adjacent its opposite outer end with one or more wrench receiving surfaces, so that the branch appliance can be turned by a wrench to displace the branch appliance inwardly (i.e., toward the center of the pipe) to compress the sealing gasket against the pipe. An inward-facing shoulder is provided on the spigot end portion for abutment on the outer surface of the pipe, within the sealing gasket. With this arrangement, the compression applied to the gasket by inward tightening of the branch is restricted to a predetermined limit. The spigot end portion is also adapted, when inserted through the pre-cut hole in the pipe, to extend a short distance beyond the aforementioned inward-facing shoulder.
The sealing gasket has at least one annular surface portion lying in a single transverse plane, and also an annular saddle-shaped lower surface adapted to conform to the surface of the pipe around the pre-cut hole. The sealing gasket is adapted to be confined between and in substantially complete conformity with the adjacent surfaces of the branch appliance, the embracement member and the pipe. The embracement member is, preferably, a continuous cylindrical tube, the opposite axial end walls of which tube slant axially, inwardly towards one another.
In another aspect of the present invention, there is provided an improved branch appliance for use with a pipe branch fitting of the general type having a cylindrical inner surface adapted for embracement around a pipe at a point where the pipe has a pre-cut hole. The embracement member has an upstanding, hollow, internally threaded boss on one side of the member, and a resilient sealing gasket is used on the inner side of the boss. According to this aspect of the invention, the improvement comprises the provision on the branch appliance of a threaded portion for retention in the threaded boss, such threaded portion having a generally planar annular surface adapted to bear rotatably on the sealing gasket, and being formed adjacent its inner end with a reduced diameter spigot end portion adapted for positioning in the pre-cut hole. The branch appliance is adapted, adjacent its opposite outer end, with one or more wrench receiving surfaces, so that it can be turned by a wrench to displace the branch appliance inwardly into the internally threaded boss, thereby to compress the sealing gasket against the pipe. The branch appliance further comprises an inward-facing shoulder adjacent to the spigot end portion for abutment on the surface of the pipe within the sealing gasket, whereby the compression applied to the gasket is restricted to a predetermined limit. In this manner, the spigot end portion is adapted, in use, to extend a short distance beyond the inward-facing shoulder. The sealing gasket has at least one upper surface portion lying in a generally transverse plane, and a saddle-shaped lower surface adapted to conform to the surface of the pipe around the pre-cut hole. The gasket is adapted to be confined between and in substantially complete conformity with the adjacent surfaces of the branch appliance, the embracement member and the pipe.